#include<iostream>
#include<cstring>
#include<cmath>
using namespace std;

double f(double x) {
	double y;
	y = 2 * x * x * x - 4 * x * x + 3 * x - 6;
	return y;

}

double my_function(double x1, double x2, double eps) {
	double x3=x1;
	while (abs(f(x3))>eps) {

		x3 = (x2+x1)/2;
		if(f(x3)*f(x2)<0){
			x1 = x3;
		}
		else{
			x2 = x3;
		}
		
	}

return x3;

}


int main() {
	double x1, x2;
	double eps;
	double y;

	cin >> x1 >> x2 >> eps;

	y = my_function(x1, x2, eps);
	
	cout<<y;


	return 0;
}
